How to remap the English/Japanese input toggle shortcut (Alt + ` ) in Google IME?

I would like to remap the Alt + ` shortcut that allows one to switch between English and Japanese input to Ctrl + Space. How can I achieve this? I presume the keys that I need to remap are Activate IME and Deactivate IME in the settings, I have tried changing the keybinds in the Google IME, but it seems that it only goes one way , where if I am in Japanese input, Ctrl + Space can go back to English, but it cannot go back to Japanese input from the English Input.

Question by Ymi on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.